FORT WORTH (CBSDFW.COM) – Fifty years ago today President John F. Kennedy and First Lady Jackie Kennedy began their day at a chamber of commerce breakfast in Fort Worth.

This morning, the chamber held a breakfast at the same hotel and their guest of honor was a man with deep ties to the Kennedy family.

Clint Hill was one of many Secret Service agents assigned to protect the Kennedys. The year had been a tough one for the first family and the trip to North Texas was the first one the Kennedy’s had taken together since they’d lost their newborn baby back in August.

“Well, its somewhat emotional knowing this was the last place President and Mrs. Kennedy were together alone, happy and content and very pleased with how things were going,” Hill told the group. “And then to have the tragedy occur just a few hours later in Dallas. So, it’s very emotional.”

Clint Hill’s job as a Secret Service agent was to protect First Lady Jacqueline Kennedy. He was with her when President Kennedy made his final speech in Fort Worth, went to Dallas and drove through Dealey Plaza.

Hill was on the running board of the car following the President’s limousine when the shots were fired. He was running to the back of the presidential limo when the third shot was fired.

“When that fatal shot was fired and hit the President in the head, because it was so explosive, it caused brain matter and blood to come out of the wound and onto the back of the car,” Hill recalled solemnly. “That’s why Mrs. Kennedy got up in the car. She was trying to retrieve some of that material and bring it back in the car. And I got up there and pushed her into the back seat trying to lie up there, forming a shield behind both the President and Mrs. Kennedy to prevent anything further from happening.”

His efforts were too late. Hill would have to cover the President’s body at Parkland Hospital with his own coat, because Jacqueline didn’t want anyone to see the massive head wound.

Hill remained assigned to Jacqueline Kennedy and her children for another year.

“The sparkle in her eyes was gone. That wonderful smile she had was very, very… few times we ever saw it again. So, she changed remarkably. She wanted to do whatever she could to make sure people remembered her husband.”

Hill suffered many tortured years reliving the moment of the assassination and asking himself, ‘what if I’d done something differently?’ The feelings remained with him until he finally revisited Dealey Plaza in 1990.

After the visit Hill said, “I came away with the conclusion I did everything I could that day. But even so, because our responsibility was to protect the President and we failed to do that I do feel that sense of guilt that we were unable to do anything to prevent the assassination from happening.”